Chris Pine isn't usually one to kiss and tell, but the blue-eyed hunk reveals why he recently split up with model Dominique Piek in OUT's June-July issue. "It's really hard in our business to maintain something," the 6-foot-1 actor admits. "For me, right now, it'd be really hard."

Pine, whose past relationships include Olivia Munn and Audrina Patridge, began dating Piek in the fall of 2011. The pair quietly split in the spring of 2013.

Though he's not looking for love at the moment, Pine acknowledges that it's not too hard to meet women in Hollywood. "Well, I'm a 32-year-old man," he says with a smile. "I feel like it's always springtime."

For now, the actor is focused on promoting "Star Trek Into Darkness." To get in shape for the international press tour, Pine completed a three-week green juice cleanse. "I can't eat pasta like I used to, even, like, a month ago. It's too much," the Los Angeles native says. "And nothing beats a good bottle of red wine and some Italian food."

Instead of logging extra hours in the gym, Pine tells the magazine he prefers to play tennis. "It's strictly for vanity," he admits, laughing. "I need accountability. I need to know that I will lose out on money if I don't show up. Otherwise, I'll be chain-smoking and drinking copious amounts of coffee. I wish I had the f---ing willpower."

The single star also opens up about his close friendship with Zachary Quinto, his co-star in 2009's "Star Trek" and 2013's "Star Trek Into Darkness." When Quinto came out publicly in a 2011 interview with New York magazine, he had Pine's full support. "I thought it was rad. It was really, really cool. He did it on his own time, on his own schedule. And Jonathan [Groff], who he's dating, is such a lovely man. He's a good guy and a great actor, and they make a fantastic couple," Pine says. "I couldn't have been happier for Zach."

Pine says he knew that Quinto was gay "from the moment I met him" -- not that it made a difference. "It was just who Zach was and that's that. I'm sensitive, and I don't ever want to make anyone feel uncomfortable. Knowing that for Zach it was more about a career thing and that he was not comfortable at the time coming out -- it was fine," Pine tells OUT. "It was something that we kind of tiptoed around and I just took it as a given, because that's what he wanted."